Description

The Perkin-Elmer Model 21 was designed as the first linear wave-number versus transmittance recording spectrophotometer. This particular instrument was built in 1952 at the original Perkin-Elmer factory in Glenbrook, Connecticut, and was purchased by the American Cyanamid Company in Stamford, Connecticut, in 1952.

Spectrophotometers determine the composition of a solution (or the concentration of certain substances within a solution) by measuring how the solution absorbs a particular wavelength of light. By varying the wavelengths in each measurement, one can take a spectrum of a solution and ascertain the composition. More advanced spectrophotometers can measure beyond the visible spectrum, providing readings for ultraviolet and infrared wavelengths.